## Problem
Both `start_workspace` and `create_workspace` chattool tools failed to
handle soft-deleted workspaces correctly.
Coder uses soft-delete for workspaces (`deleted = true` on the row).
Both tools called `GetWorkspaceByID`, which queries
`workspaces_expanded` with **no** `deleted = false` filter — so it
returns the workspace row even when soft-deleted. The only deletion
check was for `sql.ErrNoRows`, which never fires because the row still
exists.
### `start_workspace` behavior (before fix)
1. Loads the soft-deleted workspace successfully
2. Finds the latest build (a delete transition)
3. Falls through to attempt to **start** the deleted workspace
4. Produces a confusing downstream error
### `create_workspace` behavior (before fix)
1. `checkExistingWorkspace` loads the soft-deleted workspace
2. If a delete build is **in-progress**: waits for it, then falsely
reports `already_exists` — blocks new workspace creation
3. If the delete build **succeeded**: accidentally allows creation
(because no agents are found), but via fragile logic rather than an
explicit check
## Fix
Add `ws.Deleted` checks immediately after `GetWorkspaceByID` succeeds in
both tools:
- **`startworkspace.go`**: Returns `"workspace was deleted; use
create_workspace to make a new one"`
- **`createworkspace.go`** (`checkExistingWorkspace`): Returns `(nil,
false, nil)` to allow new workspace creation
## Tests
- `TestStartWorkspace/DeletedWorkspace` — verifies `start_workspace`
returns deleted error and never calls `StartFn`
- `TestCheckExistingWorkspace_DeletedWorkspace` — verifies
`checkExistingWorkspace` allows creation for soft-deleted workspaces
## Summary
When a chat's workspace is stopped, the LLM previously had no way to
start it — `create_workspace` would either create a duplicate workspace
or fail. This adds a dedicated `start_workspace` tool to the agent flow.
## Changes
### New: `start_workspace` tool
(`coderd/chatd/chattool/startworkspace.go`)
- Detects if the chat's workspace is stopped and starts it via a new
build with `transition=start`
- Reuses the existing `waitForBuild` and `waitForAgent` helpers (shared
logic)
- Shares the workspace mutex with `create_workspace` to prevent races
- Idempotent: returns immediately if the workspace is already running or
building
- Returns a `no_agent` / `not_ready` status if the agent isn't available
yet (non-fatal)
### Updated: `create_workspace` stopped-workspace hint
- `checkExistingWorkspace` now returns a `stopped` status with message
`"use start_workspace to start it"` when it detects the chat's workspace
is stopped, instead of falling through to create a new workspace
### Wiring
- `chatd.Config` / `chatd.Server`: new `StartWorkspace` /
`startWorkspaceFn` field
- `coderd/chats.go`: new `chatStartWorkspace` method that calls
`postWorkspaceBuildsInternal` with proper RBAC context
- `coderd/coderd.go`: passes `chatStartWorkspace` into chatd config
- Tool registered alongside `create_workspace` for root chats only (not
subagents)
### Tests (`startworkspace_test.go`)
- `NoWorkspace`: error when chat has no workspace
- `AlreadyRunning`: idempotent return for workspace with successful
start build
- `StoppedWorkspace`: verifies StartFn is called, build is waited on,
and success response returned
Kyle Carberry